FIG. 3 shows a schematic configuration of a conventionally used liquid chromatograph (LC). In the LC, eluent from a liquid supply unit 11 is supplied to a column 13 at a preset flow rate. An automatic injector 12 selects one sample after another from a plurality of liquid samples (not shown) in a predetermined order, extracts a preset quantity of the liquid sample selected, and injects the liquid sample into the eluent. The liquid sample injected in the eluent is carried into the column 13 by the eluent. While flowing through the column 13, the liquid sample is separated into components due to difference in the retention time. The components in the eluate from the column 13 are detected by a detector 14, which sends detection signals to a data processing unit 16. The type of detector 14 to be used is determined according to the object for the analysis. For example, a spectrophotometric detector, a fluorophotometric detector or an electric conductivity detector, is generally used as the detector 14. The data processing unit 16 processes the detection signals to build a chromatogram for each sample, and carries out qualitative analysis and/or quantitative measurement of the components by analyzing the chromatogram. A control unit 15 controls the operations of the above-described units according to an analyzing condition which is preset by the operator. A managing unit 20, consisting of a personal computer (PC) and other peripheral devices, performs several functions, such as: creating and maintaining files containing data of processing conditions, analyzing conditions, etc.; sending predetermined control signals to the control unit 15 and the data processing unit 16; and creating, saving and maintaining files containing data of the result of analysis obtained by the data processing unit 16.
Some of the parts used in the above-described LC are expendable parts, each of which is required to be replaced with a new one after the end of a limited period of time during which the part functions reliably. Sealants for preventing leakage of liquid, such as a plunger seal used in the pump of the liquid supply unit 11 and a needle seal used in the automatic injector 12, and a lamp used in the light source of a spectrophotometric detector, are examples of expendable parts. Usually, the manufacturer of every expendable part specifies the reliable working time usage limit of its product, during which the part is guaranteed to function reliably, and recommends operators to replace such parts prior to the expiration of their useable working life. The total time usage of a part is equal to the total operating time of the unit in which the part is used. For example, the time usage of the plunger seal used in the above-described pump is obtained by integrating the operating time of the liquid supply unit 11, where the integration of time is started when a new plunger seal is put in the liquid supply unit 11.
When a spectrophotometric detector is used as the detector 14 of the LC, the identification of components in the eluate and other analysis become unreliable if wavelength error occurs due to the error in the arrangement of parts of the dispersing mechanism, or due to some other errors. Therefore, a spectrophotometric detector is provided with a checking function for detecting the displacement of the wavelength actually observed from the desired wavelength preset by the operator.
In the above-described LC, the checks on the time usage of each expendable part, the accuracy of wavelength, etc., are carried out only when the operator gives a predetermined instruction to the control unit 15 or the managing unit 20. The check results (e.g. the time usage of each expendable part, the wavelength displacement, etc.) are shown in predetermined forms on displays (not shown) provided to the units, respectively. Based on the check results, the operator judges whether there is any expendable part required to be replaced, and whether the wavelength error is smaller than a preset tolerable limit. The operator carries out the tuning or the like of the spectrophotometric detector if the wavelength displacement is larger than the tolerable limit.
For assisting the operator with making the above-described judgment, the LC is provided with a software program for making a report of the check results. That is, when the program is run on the PC of the managing unit 20, all the data of the check results (the time usage of each of the expendable parts, the wavelength displacement, etc.) are shown in the form of a list. Using the software program, the operator can check whether the analyzing system is in an appropriate condition before or after a series of analyses.
In the above-described LC, a plurality of liquid samples are loaded into the automatic injector 12, and a series of analyses are carried out, automatically selecting one sample after another. As a result, it inevitably takes a very long time to complete all of the series of analyses, which is usually in the order of several hours and sometimes as long as several days. Therefore, it is highly probable that, in the midst of a series of analyses, the total time usage of an expendable part exceeds the time usage limit of the part, or the wavelength error of a spectrophotometric detector becomes larger than a preset tolerable limit. Particularly, the wavelength error is liable to exceed the tolerable limit because it is significantly influenced by environmental conditions (temperature, humidity, etc.). Accordingly, it is probable that the wavelength error exceeds the tolerable limit only in a limited period of time during a series of analyses, and again becomes smaller than the tolerable limit by the end of all the analyses.
In conventional analyzing systems of the above-described type, however, the operator cannot check the condition of the analyzing system in the midst of a series of analyses. Therefore, judgment on the reliability of the result of analysis depends principally on the result of the check carried out before the start of or after the end of the series of analyses. Using such an analyzing system is problematic in respect of reliability when the analysis is uninterruptedly continued for a very long period of time.